import React, { Component } from 'react'
class Footer extends Component {
  render () {
    return (
      <div>页面底部</div>
    )
  }
}
class App extends Component {
  render() {
    return (
      <div>
        <h1>标题</h1>
        <div>内容</div>
        <Footer />
      </div>
    )
  }
}

export default App